1. Technical Field
This invention relates to process control transmitters, and more particularly to the evaluation of potential performance degradation over time.
2. Background Information
Process control transmitters are commonly used in modern process control systems to capture data associated with any number of process variables. Pressure transmitters, for example, refer to a family of instruments having sensors constructed to measure and indicate pressure exerted typically by gases and liquids. Pressure is an expression of the force required to stop a fluid (or other substance) from expanding, and is usually stated in terms of force per unit area. A pressure transmitter generates a signal related to the pressure imposed. Typically, such a signal is electrical, but optical, visual, and auditory signals are examples of other available technologies.
Pressure sensors are used for control and monitoring in numerous everyday applications ranging from industrial processes to consumer appliances. Pressure sensors can also be used to indirectly measure other variables such as fluid/gas flow, speed, water level, and altitude. Pressure transmitters may colloquially be referred to as pressure transducers, pressure sensors, pressure senders and pressure indicators, along with other names.
Process control transmitters are relatively sophisticated, intelligent instruments, typically including accurate sensors, a processor and memory, a communications client configured for communication using a process control protocol such as HART, FOUNDATION fieldbus, FOXCOM and PROFIBUS, etc, and an on-board display, all in an industrially hardened enclosure. These instruments thus tend to be relatively expensive, and as such, it is desirable to use them for their full useful life prior to replacement. However, costs associated with degraded performance and ultimately process downtime due to unanticipated instrument failure and replacement may be many times more expensive than the cost of the instrument itself. This may encourage users to engage in an overly aggressive instrument replacement schedule, which effectively replaces transmitters which in many instances still have long remaining useful lives. A need therefore exists for a transmitter capable of addressing the aforementioned drawbacks.